I. Field of the Invention
This invention relates generally to vehicle seats, and more particularly to vehicle seats which are effectively isolated from the effects of road shock and forces due to sudden acceleration and deceleration of the vehicle.
II. Discussion of the Prior Art
It is well known that semi-tractor trucks and other truck-type commercial vehicles tend to have a relatively stiff suspension system whereby shock and vibration forces occasioned from traversing road bumps and the like are effectively transmitted to the driver or passenger to be lurched forward or rearward depending upon the magnitude of the deceleration and acceleration vectors.
To improve the comfort of the ride, it is desirable, as much as possible, to isolate the seat occupant from these types of inertial forces. There are disclosed in the prior art various systems for isolating a vehicle driver or passenger from bouncing or jolting in the vertical direction, but compensation for fore and aft translation due to acceleration and deceleration have largely not been addressed. For example, in the Thompson et al. U.S. Pat. No. 3,990,668, a vehicle seat is described which incorporates a hydraulic actuator coupled in circuit with a valve whose spool is directly connected by linkages to the seat. The valve is operative to change the response of an accumulator coupled to the actuator so as to cushion the ride and to accommodate large excursions from a predetermined ride position due to major shocks. The Thompson et al. reference has no provision for cushioning or dampening fore and aft movement of the seat system.
Other prior art patents incorporate pneumatic cylinders or air bags operate strictly to adjust the height of the seat above the floor so as to accommodate drivers/passenger of differing physical stature. In this regard, reference is made to the Costin U.S. Pat. No. 3,954,245 and the Misher et al. U.S. Pat. No. 4,638,982. Neither of these patents teaches a seat construction for minimizing or nulling out fore and aft sway of the seat under breaking and accelerating conditions, respectively.
In U.S. Pat. No. Re. 35,572, which is assigned to the assignee of the present application, a seat construction is disclosed which minimizes the fore and aft sway of the seat. The device shown in that patent uses both horizontally and vertically disposed air bags operating in cooperation with springs to dampen motion. Also utilized is a plurality of vertical hydraulic vibration dampeners. While the system described in the ""572 patent has proven to be commercially successful, it has a comparatively high cost of manufacture which impacts the profit margins achievable.
The present invention is advantageous over U.S. Pat. No. Re. 35,572 due to new concepts included in its simplified and scaled-back design. Some differences include a single air bag for dampening in the vertical direction without multiple hydraulic vibration dampeners and the use of a spring and slide rod arrangement for horizontal dampening dispensing with the need for a horizontally disposed air bag. This design enables effective isolation of forces exerted in both the vertical and horizontal direction at a substantially reduced cost. Moreover, because the stabilizing linkages and hydraulic dampener employed between the units stationary base and movable base can pivot, a greater range of vertical displacement of the seat can be achieved.
The present invention provides for a seat assembly which is adapted to be attached to the floor of a motor vehicle, such as a semi-tractor. The assembly includes a stationary base or mounting plate which is attached to the vehicle""s floor board and forms the bottom of a box-like housing. A movable base member is pivotally joined to the stationary base member by linkages. Mounted on a pedestal within the box-like housing is a means for displacing the movable base member along a path determined by the linkages. This means may comprise a vertically oriented air spring support frame which is slide mounted and free to move back and forth in the fore and aft direction when manually unlatched by the seat""s occupant, whereby the seat position can be set to accommodate the person""s stature. The upholstered seat is secured to that latter slide assembly. To dampen out any tendency of the seat to oscillate due to uneven road surfaces, a hydraulic cylinder is operatively coupled between the stationary base member and the movable base member.
A control means for adjusting the relative height of the vertically displaceable seat-supporting frame is coupled to the vertically disposed air spring. The control means allow for inflating or deflating of the air spring based upon the user""s desired seat height.
Horizontally disposed springs disposed on roller-supported, guide-rods act to cushion horizontal motions of the seat due to acceleration, braking and other generally horizontally directed forces encountered in the over-the-road travel.